Liquid dispenser

ABSTRACT

An electro-mechanical device for intermittently dispensing a liquid. The liquid is dispensed by the combination of a vessel, a cylinder having its open end exposed to the interior of the vessel, a piston, and a solenoid coupled to the piston. The piston is normally biased in a position wherein it is completely disengaged from the cylinder. When the solenoid is energized, the piston is moved to a position wherein it is engaged with the cylinder thereby pumping the liquid out of the cylinder.

' United States Patent [191 Meeks, Jr.

[451 Oct. 14, 1975 LIQUID DISPENSER [75] Inventor: Crawford R. Meeks,Jr., Culver City, Calif.

[73] Assignee: Hughes Aircraft Company, Culver City, Calif.

[22] Filed: Sept. 30, 1974 [21] Appl. No.: 510,192

[52] US. Cl. 222/189; 222/333; 222/385 [51] Int. Cl. B67D 5/58 [58]Field of Search 222/330, 189, 188, 333,

[56] References Cited UNITED STATES PATENTS 2/1936 Brady 222/333 X7/1938 Lavine 222/385 X 2,423,173 7/l947 Brady et al. 222/189 3,333,7418/1967 Radcliffe 222/189 3,521,789 7/1970 Kraft 222/334 X FOREIGNPATENTS OR APPLICATIONS 375,291 6/1932 United Kingdom 222/333 PrimaryExaminer-Robert B. Reeves Assistant Examiner-Hodd Lane Attorney, Agent,or Firm-W. I-l. MacAllister; William L. Androlia ABSTRACT Anelectro-mechanical device for intermittently dispensing a liquid. Theliquid is dispensed by the combination of a vessel, a cylinder havingits open end exposed to the interior of the vessel, a piston, and asolenoid coupled to the piston. The piston is normally biased in aposition wherein it is completely disengaged from the cylinderQWhen thesolenoid is energized, the piston is moved to a position wherein it isengaged with the cylinder thereby pumping the liquid out of thecylinder. f I

2 Claims, 3 Drawing Figures LIQUID DISPENSER FIELD OF THE INVENTIONDESCRIPTION OF THE PRIOR ART It is frequently necessary, when theenvironment is a vacuum or near vacuum and gravitational forces arecreated by centrifugal force, to provide means for dispensing liquidswhich are unaffected by the environment. Since all liquids contain tovarious degrees dissolved gases, a special problem is created by therelease of gas bubbles as the ambient pressure is lowered. Theconventional piston and cylinder pumps which exist in the prior art willnot operate in a vacuum because the inlet passages to the cylinder willnot pass the bubbles of released gas thereby trapping the gases in thecylinder. Therefore, since the released gases cannot escape from thecylinder, the pump becomes vapor locked and ceases to operate.

Several means exist in the prior art for dispensing liquids in a vacuumwhich overcome the aforementioned problems. One of such means comprisesa vessel of bellows type constuction, a check valve in the vessel, andan electro-mechanical solenoid which compresses the vessel whenenergized. When'the vessel is compressed, the check valve opens when itscracking pressure is exceeded thereby expelling deaerated liquid into aconnection tube or passageway. One major problem with this type ofdispenser is that over long periods of time repeated operations of thedispenser may cause fatigue of the bellows thereby resulting in leaksand eventual complete failure.

Another dispensing means which exists in the prior art is a pressurizedvessel with an electro-mechanical valve. In such a dispenser, when thevalve is energized, liquid is expelled from the vessel by the pressurein the vessel. A major problem with this type of dispenser is that sincethe valve is not perfect and is under continuous pressure, it may leak.

Accordingly, it is a general object of the present invention to providea liquid dispenser whose operation is unaffected by a vacuum or nearvacuum environment.

It is another object of the present invention to provide a liquiddispenser which operates in an environment where gravitational forcesare created by centrifugal force.

It is yet another object of the present invention to provide a liquiddispenser which has a long operating lifetime.

SUMMARY OF THE INVENTION In keeping with the principles of the presentinvention, the objects are accomplished with the unique combination of avessel, a cylinder having its open end exposed to the interior of thevessel, a piston having a first position wherein it is disengaged fromthe cylinder and a second position wherein it is engaged with thecylinder and a means for reciprocally moving the piston between thefirst and second position. When the piston moves from the first to thesecond position, it engages the cylinder and compresses the liquidcontained therein thereby pumping the liquid out of the cylinder.Conversely, when the piston moves from the second to the first position,it withdraws completely from and disengages with the cylinder therebyallowing both liquid to flow from the vessel into the cylinder andreleased gases, which were formerly dissolved gases in the liquid, todrift out of the cylinderand into the vessel by buoyant forces.Therefore, since the released gases are allowed to drift out of thecylinder into the vessel, the pump does not vapor lock in a near vacuumor vacuum environment.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other featuresand objects of the present invention will become more apparent byreference to the following description taken in conjunction with theaccompanying drawings, wherein like DESCRIPTION OF THE PREFERREDEMBODIMENT Referring more specifically to the drawings, FIG. 1 and FIG.2 are respectively a front elevation view and a plan view of a liquiddispenser in accordance with the teachings of the present invention.FIG. 1 and FIG. 2

are included to show the external appearance of the present inventionthereby facilitating an understanding of its nature and operation. FIG.3 is a sectional view of the present invention and contains sufficientdetail to set forth the implementation of an embodiment of the presentinvention.

Referring to the dispenser shown in FIG. 3, the dispenser includes acentral shell 2. Shell 2 is fastened to flanged base 4 by screws 6, 8,10 and 12 (shown in FIG. 2). Piston guide 14 and reservoir cover 16containing cylinder 38 defined by the walls of a cylindrical bore insaid cover 16 are fastened to shell 2 by screws 18, 20, 22 and 24 (shownin FIG. 1). Discharge valve cap 26 is fastened to reservoir cover 16 byscrews 28, 30, 32 and 34 (shown in FIG. 1). Central shell 2, flangedbase 4, piston guide 14., reservoir cover 16 and valve cap 26 constitutehousing 36 (shown in FIG. 1).

Solenoid coil 40 is enclosed by housing 36 and surrounds axially movablemagnetic core 42 which is pulled into coil 40 when the latter isenergized. Hollow piston 44 is slidably mounted in piston guide 14 andin axial alignment with cylinder 38. Furthermore, the top portion ofpiston 44 slidably engages cylindrical bore 46 of core 42 and abutsinterior shoulder 48 of cylindrical bore 46. Spring 50 is housed withincylindrical bore 46 of core 42 and surrounds piston 44. Furthermore, thetwo ends of spring 50 respectively abut exterior shoulder 52 of piston44 and piston guide 14 thereby biasing piston 44 in a position whereinthe latter is disengaged from cylinder 38.

Ball 54 is housed within discharge valve cap 26 and closes the end ofcylinder 38. Furthermore, ball 54 is loaded by a compression spring 56.Discharge tube 58 is coupled to cylinder 38 via ball 54 and spring 56.The interior of housing 36 is exposed to the ambient atmosphericpressure via vent 60. Vent 60 is closed by screen 62 which is held inplace by spacer 64 and plate 66. Plate 66 is fastened to housing 36 byscrews 69 and 70 (shown in FIG. 1).

In practice, to insure that the buoyant forces are correct, housing 36is aligned such that piston 44 is parallel to the direction of thegravitational forces.

In operation, piston 44 is normally biased by spring 50 in a positionwherein piston 44 is disengaged from cylinder 38. When coil 40 isenergized, magnetic core 42 is drawn into coil 40. Since piston 44 abutsinterior shoulder 48 of core 42, piston 44 is driven forward towardcylinder 38 by magnetic core 42. As piston 44 moves forward towardcylinder 38, spring 50 is compressed. As piston 44 engages cylinder 38and continues to move forward within cylinder 38, the liquid con tainedin cylinder 38 is forced past ball 54 and in turn forces the liquidalready in discharge tube 58 forward. Gas pressures are equalized byrelief holes 47.

When coil 40 is de-energized, spring 50, which was compressed during theforward movement of piston 44, forces piston 44 and consequently core 42back to their original positions wherein piston 44 is disengaged fromcylinder 38. Since piston 44 is disengaged from cylinder 38, liquid 68contained within housing 36 flows into cylinder 38. As liquid 68 flowsinto cylinder 38, any released gases contained within cylinder 38 driftout of cylinder 38 and into hollow piston 44 via holes 45 in said piston44. The released gases drift through hollow piston 44 and eventuallyescape housing 36 via vent 60 and screen 62. Screen 62 is made of a meshsufficiently fine such that it allows gases to pass through whileimpeding the flow of liquids.

ln all cases it is understood that the above-described embodiment ismerely illustrative of but one of the many possible specific embodimentswhich can represent application of the principles of the presentinvention. Numerous and varied other arrangements can be readily devisedin accordance with these principles by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is:

l. A liquid dispenser comprising:

a liquid-tight vessel having a vent to the exterior thereof;

a cylinder, said cylinder having its open end exposed to the interior ofsaid vessel;

a check valve, said check valve closing the opposite end of saidcylinder;

a piston, said piston having a first position wherein said piston isdisengaged from said cylinder and having a second position wherein saidpiston is engaged with said cylinder, said piston being hollow, saidpiston further communicating at one end with said vent to the exteriorand having at least one hole in the side of said piston adjacent to theother end of said piston which engages in said cylinder to vent gas fromsaid cylinder to said exterior of said vessel;

a spring, said spring biasing said piston toward said first postion; and

a solenoid coupled to said piston, said solenoid being adapted to movesaid piston from said first position to said second position when saidsolenoid is energized.

2. A liquid dispenser according to claim 1 wherein said means forventing comprises:

a passageway between said interior and said exterior of said vessel; and

a screen, said screen closing the exterior end of said passageway.

1. A liquid dispenser comprising: a liquid-tight vessel having a vent tothe exterior thereof; a cylinder, said cylinder having its open endexposed to the interior of said vessel; a check valve, said check valveclosing the opposite end of said cylinder; a piston, said piston havinga first position wherein said piston is disengaged from said cylinderand having a second position wherein said piston is engaged with saidcylinder, said piston being hollow, said piston further communicating atone end with said vent to the exterior and having at least one hole inthe side of said piston adjacent to the other end of said piston whichengages in said cylinder to vent gas from said cylinder to said exteriorof said vessel; a spring, said spring biasing said piston toward saidfirst postion; and a solenoid coupled to said piston, said solenoidbeing adapted to move said piston from said first position to saidsecond position when said solenoid is energized.
 2. A liquid dispenseraccording to claim 1 wherein said means for venting comprises: apassageway between said interior and said exterior of said vessel; and ascreen, said screen closing the exterior end of said passageway.